Method and apparatus for sensing and regulating the temperature of a fluid

Claim 2

Apparatus for sensing and regulating the temperature of a fluid comprising means for generating a first signal whenever the temperature of said fluid is lower than a preselected temperature level, said first signal having an amplitude proportional to the magnitude of the difference between the actual temperature and the preselected temperature level, means for generating a reference signal for comparison with said first signal, having a series of pulses with a predetermined frequency and amplitude, a comparator for comparing said reference signal to said first signal and for generating an output signal whenever the amplitude of said reference signal exceeds the amplitude of said first signal, and means for heating said fluid, said means being activated to heat said fluid upon receipt of said output signal, the duration of said activation being proportional to the duration of said output signal.

Claim 3

The apparatus specified in claim 1 wherein said first signal-generating means comprises means for generating a voltage in accordance with the actual temperature of the fluid.

Claim 4

The apparatus specified in claim 2 wherein said means for generating a signal in accordance with the temperature of said fluid comprises a probe for sensing the temperature of the fluid and generating a voltage having a magnitude proportional to the temperature of the fluid.

Claim 5

The apparatus specified in claim 2 wherein said means for generating a signal in accordance with the temperature of the fluid further comprises an amplifier for amplifying the voltage generated by said probe.

Claim 6

The apparatus specified in claim 2 wherein said first signal generating means further comprises a signal source for generating a voltage corresponding to the desired temperature of the fluid.

Claim 7

The apparatus specified in claim 5 wherein said first signal generating means further comprises means for comparing the voltage proportional to the actual temperature of the fluid with the voltage corresponding to the desired temperature of the fluid and generating a signal having an amplitude proportional with the magnitude of said difference.

Claim 8

The apparatus specified in claim 6 wherein said comparing means is a differential amplifier.

Claim 9

The apparatus specified in claim 6 wherein said first signal-generating means further comprises a saw-tooth wave generator, said saw-tooth generator generating a saw-tooth wave having an amplitude corresponding to the amplitude of the signal received from said comparing means.

Claim 10

The apparatus specified in claim 1 wherein said reference signal-generating means further comprises a source of alternating current.

Claim 11

The apparatus specified in claim 10 wherein said reference signal-generating means comprises a zero cross detector, said detector generating a Pulse each time a zero magnitude is detected in said alternating current source.

Claim 12

The apparatus specified in claim 1 wherein said output signal-generating means comprises means for comparing said first signal and said reference signal.

Claim 13

The apparatus according to claim 1 wherein said heating means comprises a heating unit.

Claim 14

The apparatus specified in claim 12 wherein said heating means further comprises a relay, said relay adapted to activate said heating unit.

Claim 15

The apparatus according to claim 12 wherein said heating unit comprises a relay trigger circuit adapted to energize said relay in accordance with said output signal.

Claim 16

Apparatus for sensing and regulating the temperature of a fluid comprising a probe for sensing the actual temperature of the fluid and generating a first voltage signal in accordance therewith, an amplifier for amplifying the first voltage signal generated from said probe, a voltage source generating a second voltage signal corresponding to the desired temperature of the fluid, a differential amplifier for generating a signal whose polarity is dependent upon the direction of difference between said first voltage signal and said second voltage signal and whose amplitude is proportional to the magnitude of said difference, a ramp generator for generating a saw-tooth signal whenever said first voltage signal is less than said second voltage signal and whose amplitude is proportional to the magnitude of the difference between said first and second voltage signals, an alternating current source, a zero cross detector connected to said alternating current source for generating a reference signal comprising a series of pulses one of which is generated each time said detector detects a current of zero magnitude in said current source, a comparator for comparing said saw-tooth wave and said reference signal, said comparator generating an output signal whenever the amplitude of said reference signal exceeds the amplitude of the saw-tooth wave, a heating unit, a relay to activate said heating unit, and a relay trigger circuit, said circuit activated to trigger said relay upon the receipt of an output signal from said comparator.

Claim 17

Apparatus for sensing and regulating the temperature of a fluid comprising a probe for sensing the actual temperature of the fluid and generating a first voltage signal in accordance therewith, an amplifier for amplifying the first voltage signal generated from said probe, a voltage source generating a second voltage signal corresponding to the desired temperature of the fluid, a differential amplifier for generating a signal whose polarity is dependent upon the direction of difference between said first voltage signal and said second voltage signal and whose amplitude is proportional to the magnitude of said difference, a ramp generator for generating a saw-tooth signal whenever said first voltage signal is less than said second voltage signal and whose amplitude is proportional to the magnitude of the difference between said first and second voltage signals, an alternating current source, a zero cross detector connected to said alternating current source for generating a reference signal comprising a series of pulses one of which is generated each time said detector detects a current of zero magnitude in said current source, a comparator for comparing said saw-tooth wave and said reference signal, said comparator generating an output signal whenever the amplitude of said reference signal exceeds the amplitude of the saw-tooth wave, a heating unit, a relay to activate said heating unit, and a relay trigger circuit, said circuit activated to trigger said relay upon the receipt of an output signal from said comparator.

Claim 20

The method specified in claim 16 wherein the step of generating a first signal comprises the steps of sensing the temperature of said fluid, generating a first voltage signal in accordance with said temperature, and amplifying said voltage signal.

Claim 21

The method specified in claim 17 wherein the step of generating said first signal further comprises the step of generating a saw-tooth wave whose amplitude is proportional to the amplitude of said signal.

Claim 22

The method specified in claim 18 wherein the step of generating an output signal comprises the steps of providing an alternating current source, detecting each time the magnitude of the current is zero in said source, and generating a reference signal having a pulse each time the zero current is detected in said source.

Claim 23

The method specified in claim 19 wherein the step of generating an output signal further comprises the step of comparing said saw-tooth wave and said reference signal.

Claim 24

The method specified in claim 20 wherein the step of heating the fluid comprises the steps of triggering a relay in accoRdance with duration of said output signal and activating a heating unit to heat the fluid.